DESCRIPTION: There is a substantial body of evidence demonstrating that microorganisms originating in biofilms growing inside the water lines of Dental units pose a significant risk as a source of infection. Current methods for countering this problem are of limited effectiveness. The project proposed here will lead to the development of a system suitable for use with any Dental unit that will suppress microbial growth to keep the microbial load in the effluent water below the ADA recommended level of 200 cfu/mL and gradually eradicate any existing biofilm with minimal user intervention and no consumables. The proposed system uses a combination of a photocatalytic cell to remove organisms from the incoming water stream and periodic flushing of the water line with hydrogen peroxide, generated on demand to eliminate any organisms within the water line. The proposed project will bring each of the individual components together into one unified bench-top system and demonstrate the effectiveness of that system, and particularly the novel point-of-use hydrogen peroxide synthesis cell, by using the to suppress, and eventually eradicate, the biofilm present in a used Dental unit. This project will lead to the design of a prototype unit suitable for clinical testing. PROPOSED COMMERCIAL APPLICATION: There are roughly 200,000 dentists in the U.S., with an average of 2 dental units each for a total of 400,000 dental units. Meeting ADA recommendations will require retrofitting nearly all of the dental units with a clean water system, as well as equipping all new units sold with clean water systems. The product of the proposed project will be a clean water system that can be added onto any model of dental unit, bringing that dental unit into compliance. At $500/unit, this is a potential of $200,000,000 retrofit market in the U.S., with an additional potential around the world and in continuing sales for new installations.